A six-component surrogate of diesel from direct coal liquefaction for spray analysis

Abstract

Diesel from direct coal liquefaction (DDCL) is a product from the direct coal liquefaction technology. In order to numerically investigate the atomization process of DDCL, a six-component surrogate (S1) of DDCL was developed using a model-based surrogate formulation methodology to emulate the fuel chemical and physical properties affecting the spray process and the ignition delay period. The detail compositions and the temperature-dependent physical properties (density, viscosity and surface tension) of DDCL were firstly measured in this work to provide required data for the surrogate formulation method. For comparison, two other surrogates whose number of components are four (S2) and two (S3) were created by removing some negligible components from S1. The results show that S1 can emulate all the temperature-independent and the temperature-dependent properties, while the S2 and S3 can only represent a part of these properties, especially the distillation curve of S3 seriously deviate from the experimental data with average absolute deviation of 5.82%. In general, the three surrogates can well reproduce the spray characteristics of real DDCL under the room temperature conditions. However, under the high temperature condition, the predicted evaporation rates of S2 and S3 are larger than that of S1, due to the lower distillation temperatures of S2 and S3.